fix: drain stdout in download to prevent pipe deadlock

Co-authored-by: Cursor <cursoragent@cursor.com>

src-tauri/src/services/download_manager.rs

@@ -32,7 +32,7 @@ pub fn start_download(
     }
 
     cmd.arg(url)
-        .stdout(Stdio::piped())
+        .stdout(Stdio::null())
         .stderr(Stdio::piped());
 
     let child = cmd